<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8" />
		<meta name="viewport" content="width=device-width, initial-scale=1">
		<title></title>
	</head>
	<body>
	    <script>
			var reg = /a/;
			var str = "fasfsdwqeqsdaaasfssddfeqaasdsadrerraawqewqe";
			var regRes = reg.exec(str);
			console.log(regRes);
		</script>
	</body>
</html>